carousel

carousel.js

.on('click', '.carousel .next, .carousel .prev', function(e){
        e.preventDefault();
        var self = $(this), add_elem = $('<div/>'),
            slier = self.closest('.carousel').find('ul'),
			slier_count = slier.find('.js_slide').length - 1,
			next_pos = (self.is('.next')? 1: -1)
				+ slier.find('.sel')
					.removeClass('sel')
					.index(),
			width = slier.width(),
			clear = function(){
				add_elem.remove()
				};
			
		if (next_pos < 0)
			{
			add_elem = slier.find('.js_slide:eq(0)').clone();
			add_elem.appendTo(slier);
			slier.scrollLeft(width * (slier_count + 1));
			next_pos = slier_count;
			}
		else if (next_pos > slier_count)
			{
			add_elem = slier.find('.js_slide:eq('+slier_count+')').clone();
			add_elem.prependTo(slier);
			slier.scrollLeft(0);
			next_pos = 1;
			clear = function(){
				add_elem.remove();
				slier.scrollLeft(0);
			}
			}
		slier.find('.js_slide:eq('+next_pos+')').addClass('sel');
		
        slier.stop(true, true).animate({
                scrollLeft: next_pos*width
            }, 500, clear);
        })